Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1990 Audi 100 Base, AutomaticFACTORY OEM SERVICE PROCEDURE
Deceleration Fuel Shutoff
- Warm engine to normal operating temperature. Disconnect differential pressure regulator harness connector. See Figure for location of differential pressure regulator harness connector.
- Using Adapter (VW 1315 A/1), connect Multimeter (US 1119) to differential pressure regulator and harness connector. See Figure . Set multimeter to 200 mA DC scale.
- Accelerate engine above 3000 RPM. Release throttle and note reading on multimeter. Reading should decrease to about -50 mA with throttle closed until engine speed reaches approximately 1200 RPM.
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.